The present invention is directed primarily toward a basket denester and, more particularly, toward an automatic system for automatically removing baskets, one at a time, from a stack of baskets and placing them on a horizontal conveyor. As will be seen, however, the invention can also be used to nest or stack baskets.
In a poultry packing plant, poultry parts are placed on small plastic trays and are then wrapped with a clear plastic film. These packages will ultimately be sent to a weighing station where they are weighed and a label showing the weight and price is applied. Prior to that time, however, a quantity of such trays are placed in shallow rectangularly shaped baskets for storage. These baskets which may weigh from 50 to 75 pounds each are stacked 8 high on a dolly so that the same can be wheeled around as needed.
These dollies with the baskets stacked thereon are stored in refrigerated or frozen warehouses for several hours or as much as several days. When it is desired to further process the packaged poultry, the baskets must be taken down one at a time from the top of the stack and placed on an operator table. Because of the height of the stack of baskets and the weight thereof, this has been a difficult and labor-intensive process which has resulted in many injuries to the workmen.
To Applicant's knowledge, no one has ever proposed an automated system for denesting baskets which have been vertically stacked on a movable dolly. Systems have been proposed for unstacking pallets or receptacles but none of these systems can be used to unstack such articles that may be mounted on a movable dolly. Examples of such prior art devices are shown in U.S. Pat. Nos. 3,920,152, 4,508,483 and 4,809,881.
Further, while the systems shown in the foregoing patents be useful for unstacking empty pallets or receptacles, they would not be useful for unstacking baskets such as used in the poultry industry which are filled with poultry parts. These prior art systems and substantially all other similar systems known to exist, unstack by lifting all but the lowermost item and then removing the lowermost item from the bottom. Thereafter, the entire stack is then set down and again all but the lowermost item is lifted. Lifting takes place by grippers or lifters which engage the next to the lowermost pallet or bin or the like and lift the entire stack thereabove. If the baskets were filled with poultry parts and stacked 8 high, the lifters would have to support approximately 500 pounds. It does not appear that the lifters of the prior art systems are capable of accomplishing this. Furthermore, it is doubtful that the lowermost poultry basket would be able to support all of this weight at the point where the lifters would engage the basket. There is, therefore, a need in the poultry industry for an automated system which can unstack these poultry baskets.